HUMAN GAIT

HUMAN GAIT
Prepared by:
MUHAMMAD IBRAHIM KHAN
BS.PT(Pak), MS.PT(Pak), NCC(AKUH)
INTRODUCTION TO
HUMAN GAIT
Human gait may be
define as “ the
translatory progression
of the human body as a
whole, produced by
coordinated, rotatory
movements of the body
segments” is known as
gait or human
locomotion
TASKS
Winter proposed the following five tasks for
walking:
1.
2.
3.
4.
5.
Maintenance of support of HAT
Maintenance of the upright posture and balance of the
body
Control of the foot trajectory to achieve safe ground
clearance and gentle heel or toe landing.
Generation of the mechanical energy to maintain the
present forward velocity or to increase forward velocity
Absorption of the mechanical energy for shock
absorption and stability or to decrease the forward
velocity of the body
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GAIT INTIATION
Gait initiation may be defined as a stereotyped activity that
includes the series or sequence of events that occur from
the initiation of movement to the beginning of gait cycle.
Gait initiation begins in erect standing posture with
activation of the tabilais anterior and vastus lateralis
muscles, in conjunction with an inhibition of the gastrocs
muscles, bilateral concentric contraction of the tabilais
anterior muscles results in a sagittal torque that inclines the
body anteriorly from ankles.
The CoP is described as shifting either posteriorly and
laterally toward the swing foot or posteriorly and medially
toward the supporting limb.
Abduction of the swing hip occurs almost simultaneously
with contractions of the tabilais anterior and vastus
lateralis muscle which propels the body toward the support
GAIT INTIATION
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Support limb hip and knee flex a few degrees 3-10 degree,
and the CoP moves anteriorly and medially toward the
support limb which allows the swing limb so it can leave
the ground
The Gait initiation activity ends when either the stepping
or swing extremity lifts off the ground or when heel strike
the ground.
Total duration of the initiation phase is about 0.64 seconds.
KINEMATICS
Phases of the Gait cycle
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Gait cycle which is also called as stride is the time interval
or sequence of motions which occurs between two
consecutive initial contacts of the same foot i.e. from heel
strike of the right extremity to heel strike again of the right
extremity
Distance covered one gait cycle is called the stride length
PHASES OF GAIT CYCLE
During gait cycle each extremity passes through two major
phases
1.
Stance phase----60%
2.
Swing phase-----40%
 There are two periods of “double support” in which one
extremity is in initial contact and the other one leaves the
ground
 At normal walking speed each period of double support
occupies 11% of the gait cycle which a total duration of
22% of the gait cycle, normally 20% is used
 The body is supported on a single limb for a duration
which makes 80% of the gait cycle.
DIVISONS OF PHASES
Two most common terminologies for the divisions of phases
into events of the gait cycle are
1. Traditional (T)
2. Rancho Los Amigos (RLA)
In both conventions the gait cycle is divided into percentiles
that will be used to clarify events and phases
EVENTS IN STANCE PHASES
1.
Heel contact or heel strike (T) refers to the instant at
which the heel of the leading extremity strikes the ground.
Initial contact (T and RLA) refers to the instant the foot of
the leading extremity strikes the ground. In normal gait,
the heel is the point of contact. In abnormal gait, it is
possible for the whole foot or the toes, rather than the
heel, to make initial contact with the ground. The term
initial contact will be used in referring to this event
2.
3.
4.
5.
Foot flat (T) in normal gait occurs after initial contactat
approximately 7% of the gait cycle . It is the first instant
during stance when the foot is flat on the ground.
Midstance (T) is the point at which the body weight is
directly over the supporting lower extremity. usually
about 30% of the gait cycle.
Heel-off (T) is the point at which the heel of the reference
extremity leaves the ground , usually about 40% of the
gait cycle.
Toe-off (T and RLA) is the instant at which the toe of the
foot leaves the ground , usually about 60% of the gait
cycle.
EVENTS IN SWING PHASES
1.
2.
3.
4.
Acceleration, or early swing phase (T), begins once the toe leaves the
ground and continues until midswing, or the point at which the
swinging extremity is directly under the body .
Initial swing (RLA) begins when the toe leaves the ground and
continues until maximum knee flexion occurs.
Midswing (T) occurs approximately when the extremity passes
directly beneath the body, or from the end of acceleration to the
beginning of deceleration. Midswing (RLA) encompasses the period
from maximum knee flexion until the tibia is in a vertical position.
Deceleration (T), or late swing phase, occurs after midswing when
limb is decelerating in preparation for heel strike. Terminal swing
(RLA) includes the period from the point at which the tibia is in the
vertical position to a point just before initial contact.
SWING PHASE
GAIT TERMINOLOGIES
Time and distances are two basic
parameters of motion.
1. Temporal variables
2. Distance variables
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TEMPORAL VARIABLES
1.
2.
3.
4.
5.
6.
7.
8.
Stance time
Single limb support time
Double support time
Swing time
Stride time
Step time
Cadence
speed
DISTANCE VARIABLES
1.
2.
3.
4.
Stride length
Step length
Step width
Degree of toe out
stance time
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Amount of time spent during stance phase
of Gait cycle of one extremity.
Single support time
Amount of time that spent during the period
when only one extremity is on the supporting
surface is a gait cycle
Double support time
Amount of the time spent with both feet on
the ground during one gait cycle
 The time of double support may be
increased in elder patients and in those
having balance disorders
 The time of double support decreases when
speed of walking increases
Stride duration
Amount of time spent in completion of one
stride or Gait cycle
 One stride duration for a normal stride is 1
second.
 Changes occur in stride length during
normal, slow, fast walking.
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Stride length
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Gait cycle is also called stride
The linear distance between heel strike of one extremity
and when the same extremity heel strike again ( time spent
in a gait cycle of one extremity)
A stride include two steps, right and left but stride length is
not always equal to length of two steps as there may be
unequal steps
Stride length greatly varies among individual because it is
effected by leg length, sex, age.
Stride length decreases with increase in age
Step length
Linear distance between two successive points of the opposite
extremities.
 Comparison of the right and left steps provides an
indication of gait symmetry, the more equal are the step
length more symmetrical will be the gait
Step duration
The amount of time spent in completion of a
single step.
 Its measurements is expressed as sec/step
 When there is weakness or pain in an
extremity step duration may be decreased
on the effected side while increased on the
unaffected side
cadence
The number of steps taken by a person per unit time
Cadence=number of steps/sec or min
 Shorter step length will result in increase cadence at a
given velocity
 When a person is walking with cadence between 80 and
120 steps/min, then cadence and stride length have a linear
relationship
 If cadence increases the double support time decreases and
vice versa
 Normal cadence , man=110 steps/min
 Normal cadence, woman=116 steps/min
Walking velocity
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Is the rate of linear forward motion of the body in a
specific direction
It can be measured as, cm/sec, meter/min or miles/hour
If the direction is not specified than term walking velocity
is called “walking speed”
Walking velocity or speed=distance walked/ time
Distance(cm, m, miles, km)
Time(sec, min, hour)
Step width
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Step width, or width of the
walking base
It is measured by the
linear distance between
the mid point of the heel
of one foot and the same
point of the other foot.
Step width increases if
there is increased demand
for side to side stability.
Normal is 5-10cm
Degree of toe out
It is the angle of foot placement(FP) and may
be found by measuring the angle formed by
each foot line of progression and a line which
intersect the center of heel and second toe.
 Normal angle = 7 degree
 Angle of toe-out decreases as the speed of
walking increases
Power generation and absorption
Muscle work concentrically and work
positively, produces energy which is used
for gait.
 Muscles work eccentrically and do negative
work and absorb energy
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Path of Center of Gravity
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Center of Gravity (CG):
– midway between the hips
– Few cm in front of S2
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Least energy consumption if CG travels in
straight line
CG
Path of Center of Gravity
A. Vertical displacement:
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Rhythmic up & down movement
Highest point: midstance
Lowest point: double support
Average displacement: 5cm
Path: extremely smooth sinusoidal
curve
Path of Center of Gravity
B. Lateral displacement:
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Rhythmic side-to-side movement
Lateral limit: midstance
Average displacement: 5cm
Path: extremely smooth sinusoidal
curve
Determinants of Gait
Saunder determinants
Six optimizations used to minimize
excursion of CG in vertical & horizontal
planes
 Reduce significantly energy consumption of
ambulation
 Classic papers: Sanders, Inman (1953)
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Determinants of Gait :
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(1) Pelvic rotation:
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Forward rotation of the pelvis in the horizontal plane approx. 8o on the
swing-phase side
Reduces the angle of hip flexion & extension
Enables a slightly longer step-length w/o further lowering of CG
Determinants of Gait :
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(2) Pelvic tilt:
 5o dip of the swinging side (i.e. hip adduction)
 In standing, this dip is a positive Trendelenberg sign
 Reduces the height of the apex of the curve of CG
Determinants of Gait :
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(3) Knee flexion in stance phase:
 Approx. 20o dip
 Shortens the leg in the middle of stance phase
 Reduces the height of the apex of the curve of CG
Determinants of Gait :
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(4) Ankle mechanism:
 Lengthens the leg at heel contact
 Smoothens the curve of CG
 Reduces the lowering of CG
Determinants of Gait :
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(5) Foot mechanism:
 Lengthens the leg at toe-off as ankle moves from dorsiflexion to
plantarflexion
 Smoothens the curve of CG
 Reduces the lowering of CG
JOINT MOTIONS
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The approx. ROM needed in normal gait and the time of
occurrence of the maximum flexion/extension for each
major joint may be determined by examining the joint
angels
These angles varies with age, gender, and walking speed.
Approx. values may be calculated
Anatomical position for Hip, Knee, Ankle are considered
as 0 degree, while the flexion for the hip, knee, and
dorsiflexion of the ankle is considered as positive values
and extension and planter flexion are given negative values
SAGGITAL PLANE
HIP JOINT
Hip achieve maximum flexion(approx. +20
degree) at initial contact at 0% of the gait
cycle and its most extended position
(approx. -20 degrees) at about 50% of the
gait cycle, between heel-off and toe-off
 During swing phase (mid-swing) hip joint
reaches its maximum flexion (approx. +30
degrees) which is maintained during
deaccelartion
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KNEE JOINT
The knee is straight (0 degree) at initial
contact and nearly straight just before heeloff at 40% of the gait cycle.
 During foot-flat 10% of the gait cycle the
knee reaches it maximum flexion of
(approx. +15 degree)
 During swing phase(acceleration) the knee
reaches upto 60 degree flexion at 70% of
gait cycle
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ANKEL JOINT
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The ankle reaches maximum dorsi flexion
of ( approx. +7 degree) at heel-off at 40% of
the gait cycle and reaches maximum planter
flexion( approx. -25 degrees) at toe-off 60%
of the gait cycle
JOINT MOTIONS STANCE PHASE
Sagittal Plane
JOINT MOTIONS SWING PHASE
Sagittal Plane
GRAPHICAL PRESENTATION
NORMAL WALKING
For normal walking:
 Hip: ROM approx. 20-30 degree of flexion
and extension
 Knee: ROM, 0 degree to 60 degree of
flexion
 Ankle: ROM, 25 degree planter flexion to 7
degree dorsi flexion
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*** If ROM of the above joint are not sufficient than
considerable deviation will occure from the normal gait
FRONTAL PLANE JOINT ANGLES
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During the first 20% of the stance of the gait cycle, pelvis
or the contralateral side drops about 5 degree which results
in hip adduction of the supporting limb.
The hip abducts smoothly to 5 degree of abduction,
peaking about toe-off, then returns to neutral at initial
contact
Knee remains more or less in neutral position except for a
brief abduction peaking at about 7 degrees in mid swing
and then returns to neutral position
Ankle everts from 5 degrees of inversion to 5 degree of
eversion in early stance and inverts during push-off
TRANSVERSE ANGLES
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Hip externally rotates until approx. midswing and then
internal rotates to near neutral before initial contact.
The knee joint remains relatively neutral through out most
of the gait cycle but external rotates in late stance until
about foot flat.
The ankle has three rapid reversals of rotation from about
40% of the gait cycle until initial contact and reaches a
point of maximum external rotation at about foot flat.
TRANSVERSE PLANE
STAIR GAIT
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Stair climbing is an important mode of locomotion having
many similarities to that of level ground
d locomotion, the difference between the two modes are
extremely important for the patient population
The muscle strength and ROM required for locomotion on
level ground does,t ensure that the patient will be able to
climb stairs.
The trunk ROM during level ground is similar to trunk
ROM during descent but differed from the stair gait during
ascending in all planes, trunk flexion during ascending gait
is atleaset double to that of trunk flexion in descending and
level ground gait..
STAIR GAIT
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Gait on stair is similar to level ground walking in that stair
gait involves both swing and stance phases, and to carry
HAT.
The net internal movements of the hip, knee, ankle during
stair ascending and descending when compared to level
ground walking, the internal knee extensor movement in
both ascending and descending was approx. three times
larger that that of level ground.
Ankle moments are approx. the same
Power generation mainly occur during ascending and
power generation absorption occur during descending
RUNNING GAIT
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Locomotion mode which is similar to walking, but there
are certain differences.
A person able to walk on level ground may not able to run,
running requires greater balance, muscle strength, and
ROM as walking.
Body needs greater balance as running is characterized by
reduced base due to lake of double support and the
presence of floating periods in which both extremities are
out of contact with the ground. Presence of floating periods
increases will increase the speed of the running.
Greater muscle work required to raise the HAT higher than
normal walking and to support HAT. Joints and muscles
should be able to absorb more energy to accept and control
weight of HAT.
RUNNING GAIT
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Knee is flexed about 20 degree when foot strike the ground
which also increases forces on the PF joint.
Typical base of the support is considerably less than
normal walk i.e.: 2-4inches
Both the feet falls in the same line of progression so the
center of mass of the body must be placed over single
supported foot.
To compensate for the reduced base of support the
functional varus angle increases. Which is the angle
between bisection of the lower leg and floor, it increases 5
degree during running